There are some simple things I do on a daily basis that results in common courtesy for others. Usually it's good driving habits, such as not driving in the right lane so that people can pull onto the street from side streets or businesses, etc. Or throwing my gum in the trash, so that someone else doesn't step on it. Or putting my shopping cart in the return area, instead of leaving it sit in a perfectly good empty parking spot - or rolling away into someone else's car. Some of these things are so simple, but end up being a big deal to someone else. Too bad more people don't practice these simple things, or even put their head in the game to realize what they're doing.
I walked into the bathroom at work to drop a deuce (I know, TMI). There are two toilets and two urinals. There was already a guy in the bathroom... pissing in the toilet and all over the seat - instead of simply using a urinal. He then walked out of the bathroom without flushing or washing his hands. So now the one toilet I wanted to use, that I had to wait for, has piss all over it and in it. At that point, I would've gone outside and shit on the guy's car if I knew what he was driving. Where was his mind?